Why did Cholkar give up sugar, and what was the original promise he made to Sai Baba?

Cholkar was a poor man whose job depended on passing an examination. According to Chapter 15, he made a vow to Sai Baba that if he passed, he would come to Shirdi and distribute sugar candy (khadisakhar) in Baba's name. His wish was granted, and he passed the exam. However, due to financial difficulties, there was a delay in fulfilling his vow. During this time, as a personal penance and a mark of his resolve, Cholkar gave up sugar entirely, even drinking his tea without it, until he could finally make the journey to Shirdi and complete his promised offering.